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Caption

Coloured scanning electron micrograph (SEM) of Clostridium spore formation and developmental stages, vegetative cell (left) to mature spore forming cell with large spore (right). Clostridium sp. are Gram-positive, endospore-forming, anaerobic, rod prokaryotes that occur in many environments. In their vegetative stage they rapidly undergo division and retain their thin, rod-shaped (bacillus) appearance. When environmental conditions become less favourable for normal growth the vegetative cells will to form a spore (endospore) inside the cell. Spores can remain viable for many years and will start to grow when more favourable growth conditions occur. Important Clostridium species include: Clostridium botulinum causes food poisoning (botulism), wound infections and infant botulism. Clostridium difficile a spore-forming bacteria. It is the major cause of pseudomembranous colitis and antibiotic produced diarrhoea. Magnification: x2,500 when shortest axis.